Kinetis MicrocontrollersのトピックK64F Triggering ADC on DMA major loop completion?

K64F Triggering ADC on DMA major loop completion?

davenadler — Mon, 17 Oct 2016 16:18:20 GMT

We're evaluating the K64F for an instrumentation application. We'd like to do the following:

Generate an excitation waveform using DMA-to-DAC. I got this working here:
https://community.nxp.com/message/840245
At the completion of each waveform cycle (completion of DMA major loop), generate a conversion trigger
Initiate an ADC conversion on the trigger
on ADC completion, copy the result via DMA to a buffer (ping-ponged)
When the ADC-DMA fills the buffer (completion of the DMA major loop), ping-pong to the alternate buffer and generate an interrupt signalling a load of data is ready to process
In the ADC-DMA-major-loop-completion ISR, we'll do our processing

Steps 1-5 should proceed without code intervention.

The next question is how to configure K64F to perform steps 2-3:

How do I trigger ADC conversion at the end of each DAC-DMA-major-loop completion?

Thanks in advance,
Best Regards, Dave

Re: K64F Triggering ADC on DMA major loop completion?

Hui_Ma — Tue, 18 Oct 2016 06:19:06 GMT

Customer could using ADC software trigger mode.

In Software Trigger mode, when SC2[ADTRG]=0, writes to SC1A subsequently initiate a new conversion, if SC1[ADCH] contains a value other than all 1s.

After DMA to DAC major loop finished, customer could set a major loop link to another DMA channel to transfer already ADC channel value(variable in RAM) to ADC Status and Control Registers 1 (ADCx_SC1n) as software trigger ADC conversion. For only the SC1A is used for both software and hardware trigger modes of operation. Customer could using DMA link channel to transfer data to ADCx_SC1A register as software trigger.

Customer could refer application note AN4590, which using a hardware trigger. Customer can use ADC software trigger to instead of the hardware trigger.

AN4590 software could be downloaded from here.

Wish it helps.

Have a great day,
Ma Hui
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Re: K64F Triggering ADC on DMA major loop completion?

davenadler — Tue, 18 Oct 2016 11:48:40 GMT

Sorry, I think I understand your answer; I will try:

DMA link on completion of DAC-DMA major loop to trigger for example DMA channel 2,
DMA channel 2: transfer a constant value into ADC peripheral to initiate an ADC conversion

Thanks,
Best Regards, Dave